Molting Period Research Articles

Survival of surf scoters and white-winged scoters during remigial molt

Quantifying sources and timing of variation in demographic rates is necessary to determine where and when constraints may exist within the annual cycle of organisms. Surf scoters (Melanitta perspicillata) and white-winged scoters (M. fusca) undergo simultaneous remigial molt during which they are flightless for >1 month. Molt could result in reduced survival due to increased predation risk or increased energetic demands associated with regrowing flight feathers. Waterfowl survival during remigial molt varies across species, and has rarely been assessed for sea ducks. To quantify survival during remigial molt, we deployed very high frequency (VHF) transmitters on surf scoters (n ¼108) and white-winged scoters (n ¼57) in southeast Alaska and the Salish Sea (British Columbia and Washington) in 2008 and 2009. After censoring mortalities potentially related to capture and handling effects, we detected no mortalities during remigial molt; thus, estimates of daily and period survival for both scoter species during molt were 1.00. We performed sensitivity analyses in which mortalities were added to the dataset to simulate potential mortality rates for the population and then estimated the probability of obtaining a dataset with 0 mortalities. We found thatonlyathighsurvival rates wasthere ahigh probabilityofobserving0mortalities. Weconcludethat remigial molt is normally a period of low mortality in the annual cycle of scoters. The molt period does not appear to be a constraint on scoter populations; therefore, other annual cycle stages should be targeted by research and management efforts to change population trajectories. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Evaluation of feeding various sources of distillers dried grains with solubles in non-feed-withdrawal molt programs for laying hens

An experiment was conducted using 588 Hy-Line W-36 hens (68 wk of age) to evaluate if laying hens can be successfully molted by ad libitum feeding various levels of 3 sources of distillers dried grains with solubles (DDGS). Treatment 1 consisted of a 47% corn (C):47% soy hulls (SH) molt diet (C:SH) fed for 28 d (positive control). Treatments 2, 3, and 4 were molt diets containing 94% DDGS from the 3 sources fed for 28 d. Treatments 5, 6, and 7 were 32% C: 42% SH: 20% DDGS, from each of the 3 DDGS sources, also fed for 28 d. At the end of the 28-d molt period, all hens were fed a 16% CP corn-soybean meal layer diet. Body weight loss during the molt period was significantly greater (P < 0.05) for hens fed the C:SH diet (26%) than hens fed the diets containing DDGS, and the reduction in BW loss varied among DDGS sources. Feed intake was lower (P < 0.05) for the C:SH control treatment compared with most DDGS treatments. Hens fed the C:SH diet had egg production near 0% during the last 3 wk of the molt period. Hens on the other treatments did not have mean egg production below 17% during the molt period (wk 1 to 4), and the reduction in egg production varied among DDGS sources. Postmolt hen-day egg production (5–41 wk) did not significantly differ among treatments; however, egg mass and egg specific gravity were generally reduced (P < 0.05) for hens fed the 94% DDGS molt diets compared with hens fed the C:SH diet. This study showed that molt and postmolt performance responses varied among DDGS sources; however, none of the molt diets containing 20 to 94% DDGS yielded molt period reductions in BW or egg production similar to a 47% C: 47% SH diet.

Expression and regulation of avian cathepsin L in the oviduct during molting

Cathepsins (CTSs) are peptidases that have biological roles in degrading extracellular matrix, catabolism of intracellular proteins, and processing of pro-hormones. Of these, cathepsin L (CTSL) is closely associated with morphological changes in reproductive organs required for proper function in mammals, including humans and mice, but little is known about CTSL in avian species. In the present study, the expression of CTSL was investigated in the oviduct of hens during regression and recrudescence in response to molting. Our results revealed that expression of CTSL mRNA increased (P<0.001) when the oviduct underwent regression during the molting period in hens. In situ hybridization and immunohistochemial analyses detected CTSL mRNA and protein predominantly in the luminal (LE) and glandular epithelia (GE) during regression of the oviduct, but not during regeneration of the oviduct. Expression of CTSL decreased in the oviduct of chicks treated with diethylstilbestrol (DES, a synthetic estrogen agonist). Furthermore, we discovered four miRNAs including miR-23b, miR-551, miR-1464 and miR-1803 that regulate expression of the CTSL gene at the post-transcriptional level, which suggests that CTSL mRNA can be regulated by specific miRNAs via 3′-UTR in chickens. Results of the present research suggest that estrogen regulates expression of CTSL during regression of the oviduct during molting and that down-regulation of CTSL is likely a prerequisite for the normal regeneration of oviductal tissues following molting in laying hens.

Primary wing-moult and site fidelity in South African mousebirds (Coliidae)

Based on large samples of birds mist-netted in the Eastern Cape and the Western Cape, moult of the primary remiges in both Speckled Mousebirds Colius striatus and Red-faced Mousebirds Urocolius indicus occurred throughout the year with no regional or seasonal patterns evident. The same picture emerged for the White-backed Mousebird Colius colius in the Western Cape. This aseasonality of wing-moult for all three species in South Africa was further supported by the full data set of moult records available in the Safring database. We were thus unable to use the Underhill–Zucchini model to estimate the moult parameters for these species, but an extended moult period seems likely. Recapture data for the Eastern Cape strongly suggest that Speckled Mousebirds are resident or revisit sites frequently, whereas this is not the case for Red-faced Mousebirds.

ACTH administration stimulates both cortisol and aldosterone secretion in fasting northern elephant seals (LB776)

During molting, northern elephant seals exhibit substantial alterations in circulating cortisol concentrations, probably to facilitate pelage synthesis while fasting. How these changes influence the hypothalamic‐pituitary‐adrenal (HPA) axis and the stress response, however, is not known. To investigate the modulation of the HPA axis during molting, we administered ACTH (25 units, intramuscularly) to sixteen juvenile elephant seals at the beginning (n=6), middle (n=5), and end (n=5) of their spring molting period in a cross‐sectional study design. Blood samples were collected immediately before, and then periodically for 2.5 hrs after, ACTH administration. We quantified circulating concentrations of ACTH, and the responses of cortisol and aldosterone. Both cortisol and aldosterone concentrations markedly increased following stimulation by ACTH and remained elevated for the duration of sampling (linear mixed model, F = 153, 25.3, respectively; p &lt; 0.01). There were no detectable differences in the magnitude of hormone responses to ACTH administration among the study groups (p &gt; 0.1). Nonesterified fatty acids increased following ACTH administration, suggesting upregulation of lipolysis; however, blood urea nitrogen concentrations increased only marginally, indicating that protein catabolism was less affected by ACTH administration. ACTH is not a strong aldosterone secretagogue in terrestrial mammals but several studies have measured increased aldosterone after ACTH stimulation in marine mammals, indicating its potential importance in osmoregulation during stress in these species. Cortisol and aldosterone increased in parallel following ACTH stimulation but the slope of this relationship varied among the study groups. This suggests that the release of these hormones is closely coupled in this species and possibly other marine mammals.Grant Funding Source: Supported by the Office of Naval Research

Marine moult migration of the freshwater Scaly‐sided Merganser Mergus squamatus revealed by stable isotopes and geolocators

Scaly‐sided Mergansers Mergus squamatus breed on freshwater rivers in far eastern Russia, Korea and China, wintering in similar habitats in China and Korea, but nothing was known of their moulting habitat. To investigate the moult strategies of this species, we combined wing feather stable isotope ratios (males and females) with geolocator data (nesting females) to establish major habitat types (freshwater, brackish or saltwater) used by both sexes during wing moult. Although most Scaly‐sided Mergansers of both sexes probably moult on freshwater, some males and non‐breeding and failed breeding females appeared to undertake moult migration to brackish and marine waters. Given the previous lack of any surveys of coastal or estuarine waters for this species during the moult period, these findings suggest important survey needs for the effective conservation of the species during the flightless moult period.

ACCELERATION OF TEGAL DUCK MOLTING PERIOD AND RE-LAYING USING CATTLE RETICULUM MEAL IN FEED

This research was aimed to evaluate the effect of the level of cattle reticulum meal as cholesterolsource in duck feed to accelerate molting period and post-molting re-laying process of Tegal duck.Experimental method was administered to sixty female Tegal duck aging 68 weeks old. Each treatment,comprised 3 layers with 5 repetitions, were cattle reticulum meal in feed (K), consisting of K0= 0%(control), K1 = 1.43% (equal to 0.37 g cholesterol), K2 = 2.86%, and K3 = 4.29%. The observed variableswere molting period, re-laying period, blood cholesterol level, and progesterone hormone level. Datawere analyzed by analysis of variance based on Completely Randomized Design followed by HonestlySignificant Difference Test. The result demonstrated that level of cattle reticulum meal significantlyaffected (P&lt;0.01) molting period, re-laying period, blood cholesterol and progesterone level. It wasconcluded that 1.43% cattle reticulum meal could accelerate molting period and 2.86% cattle reticulummeal could accelerate re-laying.

Variation in the stable carbon and nitrogen isotope discrimination factors from diet to fur in four felid species held on different diets

Stable carbon ( 13 C/ 12 C; d 13 C) and nitrogen ( 15 N/ 14 N; d 15 N) isotope ratios are best used to assess wild animal diets when the isotopic differences between consumers and diets are known. These differences are called discrimination factors (expressed with D notation). We report the 1st D 13 Ca ndD 15 N values between diet and fur from captive individuals held on controlled diets for 7 months and representing 4 felid species: African lions (Panthera leo), bobcats (Lynx rufus), Canada lynx (Lynx canadensis), and mountain lions (Puma concolor). All animals were fed a mix of diet items (beef, beef rib, a commercial carnivore diet, chicken, mice, rats, turkey, and turkey wings) that was consistent throughout their molting period. Weekly diet composition was determined by the percentage of mass of each diet item and overall d 13 C and d 15 N values were calculated for each animal’s diet. The mean D 13 C and D 15 N values (6 SD) between felid fur and their non–lipid-extracted diets were 1.1% 6 0.2% and 3.5% 6 0.0%, respectively (African lion, n ¼ 1 animal sampled at 2 intervals); 5.5% 6 0.5% and 4.1% 6 0.1%, respectively (bobcats, n ¼ 3); 2.4% and 3.3%, respectively (Canada lynx, n ¼ 1); and 4.7% 6 0.6% and 4.5% 6 0.2%, respectively (mountain lions, n ¼ 2). Variations in D 13 C and D 15 N values among species were likely due to dietary differences and we recommend the use of the D 13 C (5.5 6 0.5) and D 15 N (4.1 6 0.1) values obtained from the bobcats for future determinations of wild felid foraging ecology as they were held on diets composed of 100% whole animals and animal parts, which best reflects diets of wild felids.

Development of Enzymes andIn VitroDigestibility during Metamorphosis and Molting of Blue Swimming Crab (Portunus pelagicus)

The work focuses on development of digestive enzymes (amylase, total protease, trypsin, and chymotrypsin) and activity ratio of trypsin to chymotrypsin (T/C ratio) for digestive efficiency and growth, in blue swimming crab (Portunus pelagicus) during metamorphosis and molting. Specific activities of all enzyme parameters studied were associated with growth during metamorphosis, while only those of trypsin and T/C ratio were associated during molting cycle where trypsin and chymotrypsin specific activities associated with consumption rate with especially high levels during late intermolt and early premolt stages. About 50% increased weight gain was observed with at least double increased T/C ratio at the end of molting period, compared to the stages prior to molting. Growth of carapace would be more significant after finishing molting. Carapace width gain and T/C ratio were highest at the first crab stage. Studies ofin vitroprotein digestibility of different feed raw materials indicated thatArtemia, Rotifer, andMoinaare the best for larval stages. Otherwise, the use of shrimp feed andArtemiaflake could be the alternatives. Incorporating of cassava meal into the feed formula for early adult stage (juvenile) could be an advantage. The proteins from animals are more beneficial for adult crab culture than the proteins from plants and bacteria. The digestible quality of dietary protein is very important during larval stages, while the protein level of diet is more important during adult stages with fully developed digestive enzymes.

Does Feather Corticosterone Reflect Individual Quality or External Stress in Arctic-Nesting Migratory Birds?

The effects of environmental perturbations or stressors on individual states can be carried over to subsequent life stages and ultimately affect survival and reproduction. The concentration of corticosterone (CORT) in feathers is an integrated measure of hypothalamic–pituitary–adrenal activity during the molting period, providing information on the total baseline and stress-induced CORT secreted during the period of feather growth. Common eiders and greater snow geese replace all flight feathers once a year during the pre-basic molt, which occurs following breeding. Thus, CORT contained in feathers of pre-breeding individuals sampled in spring reflects the total CORT secreted during the previous molting event, which may provide insight into the magnitude or extent of stress experienced during this time period. We used data from multiple recaptures to disentangle the contribution of individual quality vs. external factors (i.e., breeding investment or environmental conditions) on feather CORT in arctic-nesting waterfowl. Our results revealed no repeatability of feather CORT within individuals of either species. In common eiders, feather CORT was not affected by prior reproductive investment, nor by pre-breeding (spring) body condition prior to the molting period. Individual feather CORT greatly varied according to the year, and August-September temperatures explained most of the annual variation in feather CORT. Understanding mechanisms that affect energetic costs and stress responses during molting will require further studies either using long-term data or experiments. Although our study period encompassed only five years, it nonetheless provides evidence that CORT measured in feathers likely reflects responses to environmental conditions experienced by birds during molt, and could be used as a metric to study carry-over effects.

Within-season nesting dispersal and molt dispersal are linked to habitat shifts in a Neotropical migratory songbird

Dispersal decisions of songbirds are relatively well understood between breeding seasons, but far less is known about dispersal between nesting attempts and during the molting period. There are several non-mutually exclusive hypotheses for why birds disperse during breeding and molt including: (1) avoiding predation, (2) because of depleted resources, or (3) seeking higher quality habitat. In this study, we evaluated the above hypotheses by radio-tracking a Neotropical migrant, the Wood Thrush (Hylocichla mustelina), during breeding and molt. During breeding, 30% (7/23) of females moved territories within-season. Females were not more likely to move off-territory following nest predation, and dispersing females were not in poorer nutritional state than non-dispersing females prior to the move. However, females occupying nest sites with large trees, high canopy height and percent canopy cover, and low percent ground cover were more likely to move off-territory for their second nest to sites with few large trees, a low canopy height and cover, and high percent ground cover. During the molting period, 61% (28/46) of birds moved off-territory to molt. Molting areas were associated with more shrubs and fruiting trees compared with breeding territories. There were no sex or age effects as to whether a bird molted on or off their breeding territory. We suggest that off-territory movements during the nesting period are to seek more suitable nesting vegetation, rather than specifically avoiding predation or because of reduced resource availability. This study has additionally shown that, without radio-telemetry, detecting off-territory movements during breeding is difficult and neglecting to include these movements may result in an underestimation of annual productivity.

MRNA expression of genes regulating lipid metabolism in ringed seals (Pusa hispida) from differently polluted areas

There is a growing concern about the ability of persistent organic pollutants (POPs) to influence lipid metabolism. Although POPs are found at high concentrations in some populations of marine mammals, for example in the ringed seal (Pusa hispida) from the Baltic Sea, little is known about the effects of POPs on their lipid metabolism. An optimal regulation of lipid metabolism is crucial for ringed seals during the fasting/molting season. This is a physiologically stressful period, during which they rely on the energy stored in their fat reserves. The mRNA expression levels for seven genes involved in lipid metabolism were analyzed in liver and/or blubber tissue from molting ringed seals from the polluted Baltic Sea and a less polluted reference location, Svalbard (Norway). mRNA expression of genes encoding peroxisome proliferator-activated receptors (PPAR) α and γ and their target genes acyl-coenzyme A oxidase 1 (ACOX1) and cluster of differentiation 36 (CD36) were analyzed in liver. mRNA expression level of genes encoding PPARβ, PPARγ and their target genes encoding fatty acid binding protein 4 (FABP4) and adiponectin (ADIPOQ) were measured in inner and middle blubber layers. In addition, we evaluated the influence of molting status on hepatic mRNA expression of genes encoding PPARs and their target genes in ringed seals from Svalbard. Our results show higher mRNA expression of genes encoding hepatic PPARγ and adipose PPARβ, FABP4, and ADIPOQ in the Baltic seals compared to the Svalbard seals. A positive relationship between mRNA expressions of genes encoding hepatic PPARγ, adipose FABP4, adipose ADIPOQ and ΣPOP concentrations was observed. These findings suggest that lipid metabolism may be affected by contaminant exposure in the Baltic population. mRNA expression of genes encoding PPARβ, PPARγ, FABP4 and ADIPOQ were similar between the mid and inner adipose layer. Hepatic mRNA expression of genes encoding PPARα and PPARγ was higher in the pre-molting individuals compared to the molting ones highlighting differential regulation of these metabolic sensors through the molting period.

Effect of Force Molting by Dietary Supplementation with ZnO and Vitamin C and Postmolting Periods on Egg Production of Broiler Breeder chickens

Zinc as Zinc Oxide at three levels (15000, 20000 and 25000ppm) with or without vitamin C was used as a method to induced molting of 296 Arbor Acres broiler breeder at 375 days old. Hens were randomly divided into eight treatments. Two treatments (T1 and T2) were free of Zinc included control with or without (1g/ kg) vitamin C; three treatments (T3, T5 and T7) included different levels of zinc (15000, 20000 and 25000ppm Zn as ZnO) without vitamin C; while, (T4, T6 and T8) included different levels of zinc (15000, 20000 and 25000ppm Zn as ZnO) with (1g/ kg) vitamin C addition. Postmolting periods were divided into 6 periods. All treatments and post molting periods had significant (P<0.05) effects on egg production traits. Hens in T4 significantly (P<0.05) better in most egg production traits. While hens in T8 had significantly (P<0.05) higher egg weight. Hens in T1 and at period 1 had significantly (P<0.05) lowest feed efficiency compared with others. Results also indicated that highest weight of eggs, number of eggs/ hen and cumulative egg/ hen for all treatments occurred during the Period 6 followed by Period 5 and 7 and the lowest number and cumulative egg/ hen was at Period 1 and 8.

Recrudescence mechanisms and gene expression profile of the reproductive tracts from chickens during the molting period.

The reproductive system of chickens undergoes dynamic morphological and functional tissue remodeling during the molting period. The present study identified global gene expression profiles following oviductal tissue regression and regeneration in laying hens in which molting was induced by feeding high levels of zinc in the diet. During the molting and recrudescence processes, progressive morphological and physiological changes included regression and re-growth of reproductive organs and fluctuations in concentrations of testosterone, progesterone, estradiol and corticosterone in blood. The cDNA microarray analysis of oviductal tissues revealed the biological significance of gene expression-based modulation in oviductal tissue during its remodeling. Based on the gene expression profiles, expression patterns of selected genes such as, TF, ANGPTL3, p20K, PTN, AvBD11 and SERPINB3 exhibited similar patterns in expression with gradual decreases during regression of the oviduct and sequential increases during resurrection of the functional oviduct. Also, miR-1689* inhibited expression of Sp1, while miR-17-3p, miR-22* and miR-1764 inhibited expression of STAT1. Similarly, chicken miR-1562 and miR-138 reduced the expression of ANGPTL3 and p20K, respectively. These results suggest that these differentially regulated genes are closely correlated with the molecular mechanism(s) for development and tissue remodeling of the avian female reproductive tract, and that miRNA-mediated regulation of key genes likely contributes to remodeling of the avian reproductive tract by controlling expression of those genes post-transcriptionally. The discovered global gene profiles provide new molecular candidates responsible for regulating morphological and functional recrudescence of the avian reproductive tract, and provide novel insights into understanding the remodeling process at the genomic and epigenomic levels.

Ketocarotenoid circulation, but not retinal carotenoid accumulation, is linked to eye disease status in a wild songbird

Pathogenic or parasitic infections pose numerous physiological challenges to organisms. Carotenoid pigments have often been used as biomarkers of disease state and impact because they integrate multiple aspects of an individual’s condition and nutritional and health state. Some diseases are known to influence carotenoid uptake from food (e.g. coccidiosis) and carotenoid use (e.g. as antioxidants/immunostimulants in the body, or for sexually attractive coloration), but there is relatively little information in animals about how different types of carotenoids from different tissue sources may be affected by disease. Here we tracked carotenoid accumulation in two body pools (retina and plasma) as a function of disease state in free-ranging house finches (Haemorhous mexicanus). House finches in eastern North America can contract mycoplasmal conjunctivitis (Mycoplasma gallisepticum, or MG), which can progress from eye swelling to eye closure and death. Previous work showed that systemic immune challenges in house finches lower carotenoid levels in retina, where they act as photoprotectors and visual filters. We assessed carotenoid levels during the molt period, a time of year when finches uniquely metabolize ketocarotenoids (e.g. 3-hydroxy-echinenone) for acquisition of sexually selected red plumage coloration, and found that males infected with MG circulated significantly lower levels of 3-hydroxy-echinenone, but no other plasma carotenoid types, than birds exhibiting no MG symptoms. This result uncovers a key biochemical mechanism for the documented detrimental effect of MG on plumage redness in H. mexicanus. In contrast, we failed to find a relationship between MG infection status and retinal carotenoid concentrations. Thus, we reveal differential effects of an infectious eye disease on carotenoid types and tissue pools in a wild songbird. At least compared to retinal sources (which appear somewhat more temporally stable than other body carotenoid pools, even to diseases of the eye evidently), our results point to either a high physiological cost of ketocarotenoid synthesis (as is argued in models of sexually selected carotenoid coloration) or high benefit of using this ketocarotenoid to combat infection.

The Flight Feather Molt of Griffon Vultures (Gyps fulvus) and Associated Biological Consequences

Molt patterns are poorly understood in most large bird species; however, they are of paramount importance in the development of surveys in which age is a key parameter. From 2000 to 2011, we studied the body condition and molt patterns of 214 Griffon Vultures (Gyps fulvus) in Spain. Adult Griffon Vultures (“griffons”) demonstrated a poor body condition in winter during the incubation period, which then improved after hatching. Conversely, subadults were fairly uniform throughout the year, with their condition slightly inferior to that of adults throughout the year (except during the incubation period). The molt period lasted from April to December, ending in winter. Juveniles started their first molt in May of their second calendar year, beginning from the innermost primary (pp1) and proceeding outwards. Later, in midsummer, some individuals molted secondaries (only 17% of secondaries were molted in the first molt season) beginning at four foci: from the innermost (ss25) outwards, the outermost (ss1) and ss5 or ss6 inwards, and centrifugally from ss12. In the third calendar year, griffons continued molting primaries outwards in an orderly fashion and two new foci appeared in secondaries, apparently at ss6 and ss15. Most juvenile feathers were completely molted by the fourth calendar year, although some fifth-calendar-year griffons had retained juvenile secondaries. Subsequently, adults did not show a consistent molt pattern, but had a high degree of asymmetry between the two wings. Some quills were molted more often than others and this led us to hypothesize that adult griffons might molt quills on demand.El conocimiento sobre los patrones de muda de la mayoría de las grandes aves es aún escaso, sin embargo resulta de fundamental importancia para desarrollar investigaciones en las que la determinación de la edad es clave. Entre 2000 y 2011 estudiamos la condición corporal y el patrón de muda de 214 individuos de Gyps fulvus en España. Los buitres adultos mostraron una condición corporal baja en invierno, durante el periodo de incubación, la cual mejoró tras el nacimiento de los pollos. Por el contrario los sub-adultos mantuvieron una condición corporal uniforme a lo largo del año, un poco más baja que los adultos a lo largo del año, exceptuando el periodo de incubación. El periodo de muda duró desde abril hasta diciembre, finalizando en el invierno. Los juveniles comenzaron su primera muda en mayo de su segundo año de calendario, iniciándola desde las plumas primarias más internas (pp1) hacia fuera. Después, a mediados del verano, algunos jóvenes mudaron las plumas secundarias (sólo el 17% de las secundarias fueron mudadas en la primera sesión de muda), comenzando en cuatro focos, desde la más interna (ss25) hacia fuera, desde la más externa (ss1), desde la ss5 o ss6 hacia dentro y centrífugamente desde las ss12. En el tercer año calendario, los buitres continuaron la muda de las primarias de forma ordenada hacia fuera y aparecieron dos focos nuevos en las secundarias, en ss6 y ss15. Para el cuarto año calendario la mayoría de las plumas juveniles estuvieron completamente mudadas, aunque algunos buitres del quinto año aún presentaban secundarias juveniles retenidas. Tras esto, los adultos no mostraron un patrón consistente de muda, con un alto grado de asimetría entre ambas alas. Algunas rémiges fueron mudadas más frecuentemente que otras, lo que nos permite hipotetizar que los buitres adultos podrían mudar las rémiges cuando fuera necesario.

Primary Molt and Body Mass Changes in Least (Calidris minutilla) and Western (Calidris mauri) Sandpipers: Patterns from Ensenada de La Paz, México

Abstract. This study documents patterns of primary feather molt and body mass changes in Least Sandpipers (Calidris minutilla) and Western Sandpipers (C. mauri) in Ensenada de La Paz, Mexico. Both species use the same habitats and complete an uninterrupted primary feather molt between late July and October. Average timing of Least Sandpiper primary molt was from 29 July to 21 September (duration of 54 days), while Western Sandpipers molted from 29 July to 29 September (duration of 62 days). Molt models of individual primaries suggested that the molt of Least Sandpipers starts after all individuals have arrived in the study area, whereas the molt of Western Sandpiper starts before all individuals have arrived; the heavier Western Sandpiper tends to grow more feathers simultaneously than the Least Sandpiper. While Western Sandpipers are heavier than Least Sandpipers at the start of molt, both species decrease their body mass over the molt period. Although Least and Western sandpipers have similar natural hi...

Molt stages and changes in digestive enzyme activity in hepatopan-creas during molt cycle of Chinese mitten crab, Eriocheir sinensis

The molt cycle of the Chinese mitten crab Eriocheir sinensis was staged by the method of Darch.We then measured the three digestive enzymes in hepatopancreas throughout the molt cycle.Based on the setogenesis and the morphological changes to the epidermis of the third maxilliped,we identified four molting periods(post-molt,intermolt,premolt and ecdysis).In addition,the premolt period was further divided into three substages(D0,D1,and D3-4).Both amylase and tryptase activities increased in the hepatopancreas during the A-B stages,peaking in the early premolt D0 stage(P0.05),and then gradually decreasing in the later premolt D3?4 stage(P0.05).There were no obvious changes in peptase activity during the majority of the molt cycle,though levels were sig-nificantly lower(P0.05) in the later premolt D3-4 stage.In summary,we identified five periods(C,D0,D1,D3-4,A-B)in the molt cycle of E.sinensis during which the activities of amylase,trypsase,and peptase changed peri-odically.

Late‐moulting Black‐necked Grebes Podiceps nigricollis show greater body mass in the face of failing food supply

From August to December, thousands of Black‐necked Grebes Podiceps nigricollis concentrate during the flightless moult period in salt ponds in the Odiel Marshes, southern Spain, where they feed on the brine shrimp Artemia parthenogenetica. We predicted that because Black‐necked Grebes moulted in a food‐rich, predator‐free environment, there would be no net loss of body mass caused by the use of fat stored to meet energy needs during remigial feather replacement (as is the case for some other diving waterbirds). However, because the food resource disappears in winter, we predicted that grebes moulting later in the season would put on more body mass prior to moult because of the increasing risk of an Artemia population crash before the moult period is completed. Body mass determinations of thousands of birds captured during 2000–2010 showed that grebes in active wing‐moult showed greater mass with date of capture. Early‐moulting grebes were significantly lighter at all stages than late‐moulting birds. Grebes captured with new feathers post‐moult were significantly lighter than those in moult. This is the first study to support the hypothesis that individual waterbirds adopt different strategies in body mass accumulation according to timing of moult: early‐season grebes were able to acquire an excess of energy over expenditure and accumulate fat stores while moulting. Delayed moulters acquired greater fat stores in advance of moult to contribute to energy expenditure for feather replacement and retained extra stores later, most likely as a bet hedge against the increasing probability of failing food supply and higher thermoregulatory demands late in the season. An alternative hypothesis, that mass change is affected by a trophically transmitted cestode using brine shrimps as an intermediate host and Black‐necked Grebes as final host, was not supported by the data.

Effect of the entomopathogenic nematode Steinernema Glaseri (Rhabditida: Steinernematidae) isolate Santa Rosa on the biological parameters of engorged nymphs of Amblyomma Cajennense (Acari: Ixodidae)

This work evaluated the in vitro effects of Steinernema glaseri on the biology of engorged Amblyomma cajennense nymphs. The ticks were exposed to infective juveniles (IJs) of S. glaseri at different concentrations. Each treatment was composed by 10 experimental units (EU = repetitions) in Petri dishes maintained at 27 ± 1º C and relative humidity (RH) &gt; 80 ± 10% for 72 hours. Then the nymphs were transferred to Petri dishes free of nematodes for observation of the following parameters: pre-ecdysis period (PEP), ecdysis period (EP), molting period (MP), ecdysis percentage (%Ec) and mortality percentage (%Mt). The groups treated with 5,000 and 10,000 IJs/EU showed significant alterations in the PEP when compared to the control, while for the EP only the treatment with 10,000 IJs/EU produced any significant changes compared to the control. The MP did not differ significantly from the control in any of the treated groups. For the %Ec only the group treated with 10,000 IJs/EU differed significantly from the control. The greatest efficiency was obtained at the concentration of 10,000 IJs/EU, in which the mortality percentage was 13%. This demonstrates that the nematode utilized was not able to cause high mortality in engorged A. cajennense nymphs and agrees with other reports indicating that immature ticks are not highly susceptible to entomopathogenic nematodes.